f-number equivalent between m43 and FF

Started Mar 25, 2014 | Discussions thread
crames Regular Member • Posts: 192
Re: Matching image size is good ?
1

bobn2 wrote:

crames wrote:

bobn2 wrote:

crames wrote:

Matching image size is not the only way to go.

I can't see how any other approach is relevant to photography. It might be to astronomy or some other branch of imaging, but for photographic purposes we have the intent of making an image to display the size we choose, not what the medium chooses, though we might choose the medium according to the size we intend to display.

It's relevant for photographers who who want to make large prints, as in "how large can I print this and still have good quality?" It's knowing whether the display size we choose is within the capability of the equipment to produce a desired quality level.

That's what I said, 'we might choose the medium according to the size we intended to display'. So, that supposes that if you choose different pixel counts according to the size that you intend to display, there is no comparing them. The high pixel count camera used to produce a very large image has gone beyond the capability of the small pixel count camera. It's only any point comparing where they are on common ground - unless your suggesting that the low pixel count camera will produce better results for small prints.

The problem is that at the "common ground" the images will have been subjected to different, or different amounts of, image processing, which doesn't necessarily result in images for comparison that are anything like the images a photographer would produce without the equal-size restriction.

Resampling images down to a common monitor resolution is one thing, they will probably tend to converge to a similar appearance. It's going in the other direction where you find the limits.

Indeed, where the lower pixel count begins to lose resolution. Still, you'd want to be comparing the same size, so you can weigh the upsampling artifacts against the well rendered noise.

One might "want to be comparing the same size," but what is the reason? Is is "so you can weigh the upsampling artifacts against the well rendered noise," even though a quality-conscious photographer might want to avoid upsampling? Or is it because photographers are somehow unable to make valid comparisons of different sized images? I'm unaware of any such restriction in the film days, so why now?

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